The present invention relates to an aqueous ink jet coating composition that comprises a blend of silicas, a blend of super and/or fully and partially hydrolyzed polyvinyl alcohols and a cationic resin. The present invention further relates to an ink jet recording material prepared from such a composition that demonstrates a balance of properties including improved imaging performance and good water resistance.
Performance requirements for ink jet recording papers are quite stringent. Such papers, for example, are required to be fast drying while allowing for ink jet printing with good image density and good color fidelity. In addition, these papers must be capable of being economically produced.
Various attempts have been made in the prior art to achieve an ink jet recording paper which satisfies each of these performance requirements. For example, U.S. Pat. No. 4,780,356 discloses a recording sheet comprising a sheet of paper and porous particles provided on the paper surface. The porous particles have an average pore size of from 10 to 5000 xc3x85, a pore volume of from 0.05 to 3.0 cc/g and an average particle size of from 0.1 to 50 xcexcm. Such particles may be coated on a paper surface by means of a binder such as polyvinyl alcohol.
U.S. Pat. No. 4,830,911 discloses a recording sheet for ink jet printers capable of forming water-resistant images by the use of an aqueous ink containing a water-soluble dye. The recording sheet is coated with a coating material containing at least one water-soluble cationic polymer, synthesized silica and polyvinyl alcohol.
U.S. Pat. No. 4,944,988 discloses an ink jet recording sheet having a coating formed on a surface thereof that comprises a pigment such as silica and various water-soluble cationic polymeric substances mixed into a water-insoluble or water-soluble resinous binder.
U.S. Pat. No. 5,013,603 discloses an ink jet recording element which comprises a paper substrate and a layer of a filler coated on the surface of the substrate. The filler comprises amorphous silica having a pore volume of more than 1.30 cc/g, and water-soluble binders.
U.S. Pat. No. 5,165,973 discloses an ink jet recording sheet which comprises an ink receptive layer of a coating material comprising both an ultra-fine anhydrous silica and a cationic polymer.
U.S. Pat. No. 5,213,873 discloses an aqueous ink jet recording sheet comprising: a substrate sheet and an aqueous ink image-receiving layer comprising (a) fine silica particles, (b) a binder consisting of at least one member selected from the group consisting of polyvinyl alcohol resins and silanol-modified polyvinyl alcohol resins, and (c) a cationic polymeric material.
U.S. Pat. No. 5,320,897 discloses an ink jet recording paper comprising a paper substrate which has been calendered and an ink receptive image-receiving layer thereon. The image receiving layer is formed by coating or saturating the substrate with an aqueous composition comprising a porous pigment such as silica, water soluble binder and/or cationic resin.
U.S. Pat. No. 5,541,002 discloses a printing paper comprising a paper substrate and a coating layer formed on at least one side of the substrate. The coating layer is formed from a coating composition comprising a white pigment such as amorphous silica and a water-soluble resin such as fully saponified polyvinyl alcohol and partially saponified polyvinyl alcohol.
U.S. Pat. No. 5,660,622 discloses a coating composition for ink jet recording sheets which includes a combination of hydrated amorphous synthetic silica, a synthetic binder, a cationic agent, a leveling-flow modifier, a dispersing agent, an optical brightener, remainder water.
U.S. Pat. No. 5,747,146 discloses a printing medium comprising a base material and an ink-receiving layer which comprises inorganic fine particles such as silica and a resin such as polyvinyl alcohol or modified polyvinyl alcohol.
U.S. Pat. No. 5,753,082 discloses a coating composition for ink jet recording which comprises a pigment such a synthetic silica, a water-base binder and a water-soluble cationic polymer.
U.S. Pat. No. 5,804,293 discloses a coating composition for recording paper that comprises (a) composite particulate amorphous precipitated silica, (b) aqueous solvent, and (c) water-soluble organic polymeric binder dissolved in the aqueous solvent.
U.S. Pat. No. 5,856,001 discloses an ink jet recording medium comprising a substrate and an ink receiving layer formed on the substrate. The ink receiving layer comprises porous xerogel pigment particles such as amorphous silica, a binder such as polyvinyl alcohol and cationic polymer, and further contains lubricants.
In addition, ink jet recording papers prepared from coating compositions made up of a blend of silicas and a super hydrolyzed polyvinyl alcohol binder have been sold by Kanzaki Specialty Papers Inc. under the trade designation KS-JET PREMIUM(copyright) ink jet recording papers.
Although some of these ink jet recording papers perform satisfactorily in terms of functional performance requirements, improvement in the area of imaging performance (e.g., intercolor bleeding and optical density) is still needed.
A need therefore exists for an ink jet recording material that demonstrates a balance of properties including improved imaging performance.
It is therefore an object of the present invention to provide such an ink jet recording material.
It is a more specific object of the present invention to provide an ink jet coating composition that allows for improved imaging performance.
It is a further object to provide an ink jet recording material prepared from such a coating composition that demonstrates a balance of properties including improved imaging performance and good water resistance.
The present invention therefore provides an aqueous ink jet coating composition that demonstrates a balance of properties including improved imaging performance and good water resistance and that comprises a blend of silica particles, a blend of super and/or fully and partially hydrolyzed polyvinyl alcohols, and a cationic resin.
Preferably, the inventive coating composition comprises:
a. from about 40 to about 95 percent by weight (% by wt.) (dry basis) (based on the total weight (dry basis) of pigment composition and water-soluble binder) of a pigment composition comprising a blend of silica particles, wherein a first quantity of silica particles has a pore volume ranging from about 1.4 to about 3.0 cubic centimeters per gram (cc/g) and an average particle size ranging from about 1 to about 17 microns (xcexc), and wherein a second quantity of silica particles has a pore volume ranging from about 0.6 to about 1.3 cc/g and an average particle size ranging from about 1 to about 17xcexc;
b. from about 60 to about 5% by wt. (dry basis) (based on the total weight (dry basis) of pigment composition and water-soluble binder) of a water-soluble binder comprising a blend of super and/or fully and partially hydrolyzed polyvinyl alcohols; and
c. from about 1 to about 30% by wt. (dry basis) (based on the total weight (dry basis) of the coating composition) of a cationic resin.
The present invention further provides an ink jet recording material having an ink receptive layer on a substrate, said ink receptive layer being the aqueous ink jet coating composition identified above.
The foregoing and other features and advantages of the present invention will become more apparent from the following description.
An ink jet recording material according to the present invention is characterized by having an ink receptive layer on a substrate, said ink receptive layer being an aqueous composition containing a pigment composition, a water-soluble binder and a cationic resin as its main components.
As a result of various studies concerning the ink receptive layer (aqueous composition), the present inventors have found that recorded images that have or demonstrate high image densities, low intercolor bleeding and good water resistance are produced when a blend of silicas and a blend of super and/or fully and partially hydrolyzed polyvinyl alcohols are used in the ink receptive layer of the inventive recording material.
The pigment composition of the aqueous ink jet coating composition of the present invention comprises a blend of silica particles. The silica blend is made up of: a first quantity of silica particles having a pore volume ranging from about 1.4 to about 3.0 cc/g and an average particle size ranging from about 1 to about 17xcexc; and a second quantity of silica particles having a pore volume ranging from about 0.6 to about 1.3 cc/g and an average particle size ranging from about 1 to about 17xcexc.
Silicas useful in the subject pigment composition include amorphous precipitated silicas, reinforced amorphous precipitated silicas, colloidal silica dispersions, fumed silicas, wax-free silica gels, and wax surface-treated silica gels, with preferred silicas being wax-free silica gels and wax surface-treated silica gels.
Specific preferred examples of silica particles having pore volumes and average particle sizes falling within the ranges specified for the first quantity of silica particles include SYLOID 234 wax-free silica gels and SYLOID 7000 wax surface-treated silica gels marketed by Grace Davison, W. R. Grace and Co., 7500 Grace Drive, Columbia, Md. 21044 (xe2x80x9cGrace Davisonxe2x80x9d).
A specific preferred example of silica particles having a pore volume and average particle size falling within the ranges specified for the second quantity of silica particles is SYLOID 620 silica gel, also marketed by Grace Davison.
The subject pigment composition may also contain alumina trihydrate, clays, calcined alumina, calcined clays, calcium carbonate and the like provided that any such additional component(s) does not serve to adversely impact upon the imaging performance properties of the pigment composition.
In a preferred embodiment, the pigment composition comprises:
a. from about 10 to about 90% by wt. of silica particles having a pore volume ranging from about 1.5 to about 2.5 cc/g and an average particle size ranging from about 1 to about 14xcexc; and
b. from about 90 to about 10% by wt. of silica particles having a pore volume ranging from about 0.6 to about 1.2 cc/g and an average particle size ranging from about 5 to about 17xcexc.
In a more preferred embodiment, the first quantity of silica particles comprises a blend of a wax-free silica gel and a wax surface-treated silica gel.
The water-soluble binder of the aqueous ink jet coating composition of the present invention comprises super and/or fully and partially hydrolyzed polyvinyl alcohols. The subject binder serves to enhance the coatability of the coating composition and further serves to reduce or eliminate dusting in the resulting recording material, while improving printability.
The subject binder may contain additional components (e.g., gelatin, casein, alginate, water soluble gums, cellulose derivatives, CMC, hydroxymethyl cellulose, hydroxypropyl cellulose, modified starch, ethoxylated starch, cationic starch, oxidized starch, polyvinyl pyrrolidone, amphoteric latex, maleic anhydride resins, polyester resins, polyacrylamide resins, melamine resins, polyvinyl acetate, acrylic vinyl polymers, and blends thereof) provided any such additional components(s) does not adversely impact upon the desirable properties of the binder.
The term xe2x80x9csuper hydrolyzed,xe2x80x9d as used herein, is intended to refer to those polyvinyl alcohols having a% hydrolysis ranging from about 99.3 to about 100, while the term xe2x80x9cfully hydrolyzedxe2x80x9d refers to a% hydrolysis ranging from about 98 to about 98.8. The term xe2x80x9cpartially hydrolyzed,xe2x80x9d on the other hand, denotes a polyvinyl alcohol having a% hydrolysis of from about 70 to about 97.
In a preferred embodiment, the partially hydrolyzed polyvinyl alcohol of the binder of the aqueous ink jet coating composition of the present invention has a% hydrolysis of from about 84 to about 92.
The super, fully and partially hydrolyzed polyvinyl alcohols of the water-soluble binder have preferred molecular weight ranges of from about 5,000 to about 186,000 (preferably from about 13,000 to about 150,000) and may be modified by adding a cation thereto. More specifically, the polyvinyl alcohols may be modified by silanol, carboxy and/or quaternary amine groups.
The subject binder preferably has a medium-to-low viscosity. More specifically, the binder has a preferred viscosity ranging from about 3 to about 80 centipoise (cps), as measured by a Brookfield Viscosimeter, model number DV-II+, using a 4% polyvinyl alcohol aqueous solution at 20xc2x0 C.
A specific preferred example of a super hydrolyzed, medium viscosity polyvinyl alcohol is available from Air Products and Chemicals, Inc., 7201 Hamilton Blvd., Allentown, Pa. 18196-1501 (xe2x80x9cAir Productsxe2x80x9d) and is sold under the trade designation AIRVOL 125. Preferred medium and low viscosity partially hydrolyzed polyvinyl alcohols are also available from Air Products and are sold under the trade designations AIRVOL 523 and AIRVOL 205, respectively.
In a preferred embodiment, the water-soluble binder of the aqueous ink jet coating composition is a blend that comprises:
a. from about 10 to about 90% by wt. (more preferably from about 20 to about 80% by wt.) of a super hydrolyzed, medium viscosity polyvinyl alcohol;
b. from about 10 to about 70% by wt. (more preferably from about 15 to about 65% by wt.) of a partially hydrolyzed, medium viscosity polyvinyl alcohol; and
c. from about 0 to about 20% by wt. (more preferably from about 5 to about 15% by wt.) of a partially hydrolyzed, low viscosity polyvinyl alcohol.
In a more preferred embodiment, the binder further comprises from about 1 to about 50% by wt., based on the total weight of the binder, of a cationic starch. The cationic starch serves to improve surface strength, coatability and printability. Suitable examples of such a cationic starch include corn, potato, rice, tapioca, waxy maize and wheat. In a preferred embodiment, the cationic starch is waxy maize or amylopectin polymer.
The cationic resin of the aqueous ink jet coating composition of the present invention serves as a fixing agent of ink and improves the fixing of recorded images and water resistance.
Preferred cationic resins include polyvinyl benzyl trimethyl ammonium chloride, polydiallyl dimethyl ammonium chloride, polymethacryloxyethyl hydroxy ethyldiammonium chloride, quaternary acrylic copolymer latex, amidoepichlohydrin copolymer, dimethylaminoethylmethacrylate copolymer, vinyl pyrrolidone dimethylaminoethylmethacrylate copolymer, polyallylamine, polyvinylamine, vinyl amine acrylonitrile copolymers, polyalkylene imine polymers, polyalkylene polyamine polymers, polyalkylene polyamide dicyandiamide copolymers, polyamide dicyandiamide copolymers, quaternary ammonium polymers and blends thereof. In a preferred embodiment, the cationic resin is a quaternary ammonium polymer and, more preferably, is polydiallyl dimethyl ammonium chloride marketed by Calgon Corporation, 2015 Christine Drive, Harleysville, Pa. 19438 under the trade designation CP-1030.
The cationic resin is present in the inventive aqueous ink jet coating composition in an amount ranging from about 1 to about 30% by wt., preferably from about 3 to about 15% by wt., based on the total weight of the dry coating composition. The present inventors have found that if the cationic resin is present in an amount below 1% by wt., the water resistance of the composition is very poor, and if the cationic resin is present in an amount above 30% by wt., printed image quality is adversely affected.
In addition to the above components, the aqueous ink jet coating composition of the present invention can advantageously contain other additives such as antioxidants, crosslinking agents, defoaming agents, dispersing agents, mold inhibitors, slip agents, UV absorbers, wetting agents and whitening agents. However, some such additives may adversely impact upon the desirable properties of the resulting ink jet recording material.
Preliminary studies have indicated that wax emulsion slip agents and, more specifically, polyethylene wax dispersions, may advantageously affect not only the frictional properties of the resulting recording material but also the wicking, bleeding and photoimaging properties of the material. A preferred polyethylene wax dispersion slip agent is manufactured by Michelman Inc., 9080 Shell Road, Cincinnati, Ohio 45236 (xe2x80x9cMichelmanxe2x80x9d) under the trade designation MICHEM 61335 high density polyethylene wax dispersion.
In a preferred embodiment, the aqueous ink jet coating composition of the present invention comprises:
a. from about 50 to about 90% by wt. (dry basis) (based on the total weight (dry basis) of pigment composition and water-soluble binder) of a pigment composition comprising a blend of silica particles, wherein a first quantity of silica particles has a pore volume ranging from about 1.5 to about 2.5 cc/g and an average particle size ranging from about 1 to about 14xcexc, and wherein a second quantity of silica particles has a pore volume ranging from about 0.6 to about 1.2 cc/g and an average particle size ranging from about 5 to about 17xcexc;
b. from about 10 to about 50% by wt. (dry basis) (based on the total weight (dry basis) of pigment composition and water-soluble binder) of a water-soluble binder comprising a blend of super and/or fully and partially hydrolyzed polyvinyl alcohols; and
c. from about 3 to about 15% by wt. (dry basis) (based on the total weight (dry basis) of the coating composition) of a cationic resin.
In a more preferred embodiment, the inventive coating composition further comprises from about 1 to about 30% by wt. (dry basis) (based on the total weight (dry basis) of the coating composition) of a high density polyethylene wax emulsion slip agent.
It is noted that preliminary studies have indicated that the pigment composition and water-soluble binder of the present invention advantageously affect the L, a, b output and perceived hue and intensity of color images printed on the resulting ink jet recording material.
The inventive coating composition is prepared by mixing the components with water so as to obtain an aqueous composition having a solids content ranging from about 16 to about 19%, based on the total weight (dry basis) of the coating composition.
The substrate of the ink jet recording material of the present invention may be prepared from any suitable natural and/or synthetic fiber. For example, the substrate may be prepared from chemical, mechanical and/or recycled paper-making fibers. Polyester, vinyl acetate and/or polypropylene synthetic types of fibers may also be used.
The substrate preferably has a thickness ranging from about 100 to about 280xcexc, a basis weight ranging from about 70 to about 200 grams per square meter (g/m2), and a surface smoothness of from about 10 to about 50 Bekk seconds.
The ink jet recording material of the present invention is obtained by coating at least one surface of the substrate with the aqueous coating composition and then drying the resulting layer to form an ink receptive layer on the substrate surface.
The aqueous coating composition of the present invention may be applied to the substrate surface using e.g., air knife coaters, rod coaters or gravure coaters. As will be readily appreciated by those skilled in the art, silica-based coating compositions are highly viscous even at low solids loadings. As a result, such compositions are not amenable to high shear coating applications such as those that involve the use of e.g., blade coaters.
In order to avoid degradation in ink absorptivity caused by the use of excessive amounts of coating, it is preferred that the coating composition of the present invention be applied so as to achieve an average coat weight that ranges from about 2 to about 16 g/m2, based on the total weight (dry basis) of the coating composition.
Drying can be accomplished by any known method or technique including room temperature air drying, hot air drying, heating surface-contact drying or heat radiation drying.
The ink jet recording material of the present invention demonstrates a balance of properties including improved imaging performance and good water resistance. In addition, the inventive material preferably has a coefficient of friction (COF) below about 0.55 and, more preferably, from about 0.2 to about 0.4. Multifeeding during desktop printing operations is therefore reduced or eliminated.